Ground or earth connections are used in electrical circuits for a wide variety of purposes. Earth or ground connections provide a potential against which other potentials can be referenced. Earth or ground connections also have safety functions, for example for preventing the build up of static electricity and for preventing persons getting electric shock in case of insulation failure. Furthermore, ground connections are often necessary for the correct function of an EMC filter in an electric circuit.
In the context of electrical engineering, the terms “ground” and “earth” typically have the same meaning. The terms are used interchangeably in this document.
In many circumstances, electrical circuits will function regardless of whether a ground or earth connection of the circuit is correctly attached to ground/earth. However, such circuits may be potentially unsafe to a user. Alternatively, or in addition, such circuits may be vulnerable to damage, for example due to transient overvoltage on the mains supply e.g. caused by lightning.